Transformers may be used in many different types of power distribution systems, such as in voltage (or power) converters. Power converters may not be fully integrated on-chip for a variety of reasons. For example, power converters may be designed at 0.1 to 10 MHz operating frequencies. On-chip inductors may not be used because the amount of inductance needed for a circuit such as a Buck converter at these frequencies is large. Additionally, the physical size of inductors may be too large with certain magnetic materials. Still further, in high-frequency inductors, magnetic materials may not be used because their frequency range has been limited to less than 100 MHz.
There are advantages to integrating a power distribution system on the same die as the circuits that are powered by the power distribution system. For example, as processor technology scales to smaller dimensions, supply voltages to circuits within a processor may also scale to smaller values. But for many processors, power consumption has also been increasing as technology progresses. Using an off-die voltage converter to provide a small supply voltage to a processor with a large power consumption may lead to a large total electrical current being supplied to the processor. This may increase the electrical current per pin, or the total number of pins needed. Also, an increase in supply current may lead to an increase in resistivity as well as inductive voltage drop across various off-die and on-die interconnects, and to a higher cost for decoupling capacitors. Integrating the voltage (or power) converter onto the die may mitigate these problems.